Abstract: A fluid compressor 10 comprising a stator 22, having a bore shaped first chamber 26 and an annular second chamber 30, and a piston 18 comprising a central piston rod 36 having a first piston head 44 and a concentrically arranged cylindrical piston sleeve 38 having a second piston head 48. The stator 22 and piston 18 together define a first compression chamber 12, a second compression chamber 14 provided concentrically around the first chamber 12, and a third compression chamber 16 provided concentrically around the first chamber 12 and linearly with the second chamber 14. The compression chambers 12, 14, 16 are interconnected via intercooling conduits 72, 74. A hydraulic actuator 20 is coupled to the piston 18 by a hydraulic ram 82. During left to right movement of the piston 18 fluid enters the third chamber 16 and fluid is compressed in the second chamber 14.

Abstract: A torque applying tool such as a nutrunner or torque wrench incorporates torque sensors responsive to strain in a shaft mounting an output square drive head the strain being measured as it exists immediately adjacent the drive head. The shaft is a hollow quill shaft an outer diameter of which is splined to receive a torque drive input at a location axially spaced from the drive head. A central shaft extends from the drive head centrally up the quill shaft and a flexible cantilever beam is mounted between a cranked end of the central shaft as it extends out of the quill shaft and the corresponding end of the quill shaft. One or more strain sensing transducers, preferably S.A.W. devices, are mounted on the cantilever beam to detect flexure of the beam, and the resulting output signal is passed through an inductive or capacitive coupling for transmission to a CPU and display.

Abstract: A torque sensing calibration unit comprises a hollow torsion bar (2) to which torque is to be applied, associated with two or more pairs or positions sensors (10, 11, 12, 13, 14, 15) each pair being arranged to measure movement of the bar on diametrically opposite sides of a central axis through the bar (2). The pairs of sensors are arranged to measure movement in mutually perpendicular directions.